The present invention relates to motorized window shades, and, more particularly to shades for inclined or curved windows mounted in vehicles, such as recreational vehicles (RVs), especially those windows in cab-over locations of Class B RVs.
A wide variety of window shades have been used. In general, these shades permit the users to selectively cover and uncover some or all of a window opening, as desired to control the amount of light coming into a window and/or to control visibility through the window. For the convenience of the user, and especially where the window is less readily accessible, some prior window shades have been operable via motors. Motorized shades can perform their function well in connection with modest sized, vertical windows in static structures, such as those windows found in traditional residences.
However, motorized shades tend to be more expensive than manually operable shades, and typically require more bulky mechanisms. For example, manually operable shades may not have the same top-to-bottom alignment problems in use, because only a single roller can suffice, with bottom “fall” being adjustable by the using during actuation. Motorized shades using top and bottom rollers, however, usually need a means of ensuring proper alignment between the rollers, especially over an extended period of time. Alignment solutions which have been available for those motorized shades often employ heavy, expensive, and/or oversized frames or structural features.
Further, motorized (as well as manual) shades used in static structures have run into operational difficulties where the window to be covered is inclined with respect to the vertical plane and/or has a curvature into the horizontal plane. Especially in connection with wide windows, using shades with inclined or curved windows runs the risk of shade sag, or spacial separation from the desired window distance to be maintained by the shade from the window. Prior shades have reduced sag by forming the shade web from rigid material, but that often increases shade cost and weight. Other attempts to prevent or reduce shade sag have involved the use of guide wires and/or web tensioning rollers at the bottom of the shade. However, in addition to increasing cost and overall weight of the shade assembly, such devices increase the actuation torque needed by operating motors (often requiring a larger and/or more expensive motor) or the force needed to be exerted by the manual user.
Further, using shades in vehicles can create additional difficulties. Spacial constraints in vehicles are generally more severe than in static structures. For example, window openings in vehicles are often shrouded or shielded with respect to the adjacent wall structure. Thus, whatever shade is to be used should conform to the wall thickness if significant intrusion into the users space of the vehicle is to be avoided. This can, for example, be on the order of only a couple inches of lateral space, and sometimes less.
Also, since it is usually desirable to keep overall vehicle weight low, for a variety of reasons (including fuel economy), component weight should be minimized as well. Thus, some of the frame and support structures that may be acceptable for motorized shades in static structures is not well suited for use in vehicles. Similarly, costs that may be acceptable for motorized shades in residences and office buildings are not acceptable for production of vehicles, where the user market for vehicles can be much more price sensitive.
These concerns about applying prior motorized shade assemblies to vehicles are often heightened and/or compounded in connection with RVs. Windows in RVs, such as Class B motorhomes, can be found, for example, in the cab-over sleeping compartment. Such windows are, for example, curved and/or inclined, with the bottom portion being relatively inaccessible to the user without significant effort. Also, it is sometimes preferable to make such cab-over windows relatively wide, extending nearly the width of the RV. For user safety, insulation, and/or aesthetic appeal, cab-over windows often have an interior molded plastic shroud (formed from ABS, for example) closely spaced from the window. Prior attempts to use motorized shades for such cab-over windows have encountered shade sag, snagging of the shade web with the side and/or bottom edges of the shroud opening, and misalignment of the shade (even when using cord draw strings, since the “winding diameter” can be non-uniform from time to time). These prior attempts have also involved motorized shades whose cost, installation time, and maintenance have been undesirably high. Also, it can be important in RVs to keep the electric power requirements of feature motors to a minimum, as that the RV has less costly and/or heavy battery requirements when camping remote from an external source of electric power.